U.S. patent application number 14/591789 was filed with the patent office on 2016-07-07 for method for adjusting a grille shutter opening.
The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Mohannad Hakeem, Eric Krengel, Patrick Shearer, Gopichandra Surnilla, Joseph Patrick Whitehead, Shuya Shark Yamada.
Application Number | 20160194999 14/591789 |
Document ID | / |
Family ID | 56133465 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160194999 |
Kind Code |
A1 |
Hakeem; Mohannad ; et
al. |
July 7, 2016 |
METHOD FOR ADJUSTING A GRILLE SHUTTER OPENING
Abstract
Methods and systems are provided for adjusting a grille shutter
opening based on an estimated amount of fuel in oil dilution. In
one example, a method may include adjusting a grille shutter
opening to a closed position in response to an oil dilution amount
above a threshold, the position determined based on the oil
dilution amount in addition to each of engine coolant temperature
and acceleration/deceleration.
Inventors: |
Hakeem; Mohannad; (Dearborn,
MI) ; Yamada; Shuya Shark; (Novi, MI) ;
Shearer; Patrick; (Allen Park, MI) ; Whitehead;
Joseph Patrick; (Belleville, MI) ; Krengel; Eric;
(Dearborn, MI) ; Surnilla; Gopichandra; (West
Bloomfield, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Family ID: |
56133465 |
Appl. No.: |
14/591789 |
Filed: |
January 7, 2015 |
Current U.S.
Class: |
123/41.05 ;
123/41.04 |
Current CPC
Class: |
F02M 26/00 20160201;
F01P 7/026 20130101; B60K 11/085 20130101; F01M 13/00 20130101;
F01P 7/12 20130101; F01M 2013/0077 20130101; F01P 7/16 20130101;
F01M 2001/165 20130101; F01M 5/007 20130101; F01M 1/16 20130101;
F01P 7/10 20130101 |
International
Class: |
F01P 7/10 20060101
F01P007/10; F02M 25/07 20060101 F02M025/07; F01M 13/00 20060101
F01M013/00; F01P 7/12 20060101 F01P007/12; F01M 5/00 20060101
F01M005/00 |
Claims
1. A method, comprising: adjusting a grille shutter opening
responsive to fuel in oil dilution.
2. The method of claim 1, wherein the adjusting includes adjusting
an angle of opening from a first mid-point position to a second,
different, mid-point position.
3. The method of claim 2, wherein a mid-point position is an angle
of opening between a fully open grille shutter and a fully closed
grille shutter.
4. The method of claim 1, wherein the adjusting is responsive to an
estimated fuel in oil dilution level, the estimate based on intake
air oxygen sensor measurements.
5. The method of claim 1, wherein the adjusting is performed when
push-side PCV flow is active, and not performed when push-side PCV
flow is inactive.
6. The method of claim 5, further comprising: in response to
push-side PCV flow being inactive, selectively activating push-side
PCV flow based on boost conditions.
7. The method of claim 1, wherein the adjusting is not performed
when one or more of an EGR valve and a fuel vapor purge valve are
open.
8. The method of claim 1, further comprising: adjusting a grille
shutter opening further based on one or more of coolant
temperature, charge air cooler temperature, and vehicle
acceleration/deceleration.
9. The method of claim 8, further comprising: in response to one or
more of coolant temperature above a threshold temperature and
vehicle deceleration, delaying the adjustment of grille shutters
based on fuel in oil dilution.
10. A method for an engine front-end airflow adjusting device,
comprising: selectively adjusting the engine front-end airflow
based on a coolant temperature, and in response to an oil dilution
amount above an upper threshold, selectively adjusting the engine
front-end airflow based on each of the coolant temperature and the
oil dilution amount.
11. The method of claim 10, wherein adjusting the engine front-end
airflow includes: one of increasing or decreasing the engine
front-end airflow, and adjusting the front-end airflow adjusting
device from a first position to a second position.
12. The method of claim 10, wherein increasing the airflow includes
adjusting the engine front-end airflow adjusting device from a
fully closed position to a fully open position, and decreasing the
airflow includes adjusting the engine front-end airflow adjusting
device from a fully open position to a fully closed position.
13. The method of claim 10, wherein increasing the engine front-end
airflow includes adjusting the engine front-end airflow adjusting
device from a first mid-point position to a second mid-point
position, the second mid-point position more open than the first,
and decreasing the engine front-end airflow includes adjusting the
engine front-end airflow adjusting device from a first mid-point
position to a second mid-point position, the second mid-point
position less open than the first.
14. The method of claim 10, wherein adjusting the engine front-end
airflow based on each of the coolant temperature and the oil
dilution amount includes: decreasing the engine front-end airflow
in response to the coolant temperature at or below an upper
threshold temperature and the oil dilution above the upper
threshold amount, and increasing the engine front-end airflow in
response to the coolant temperature above the upper threshold
temperature and the oil dilution above the upper threshold
amount.
15. The method of claim 10, wherein the oil dilution amount is
estimated via intake air oxygen sensor measurements during
conditions wherein push-side PCV flow is active.
16. The method of claim 10, wherein the engine front-end airflow
adjusting device is an adjustable grille shutter.
17. A method for an engine front-end airflow adjusting device,
comprising: adjusting the engine front-end airflow based on each of
vehicle acceleration/deceleration and engine temperature, and in
response to an oil dilution amount above an upper threshold,
adjusting the engine front-end airflow based on each of
acceleration/deceleration, engine temperature, and the oil dilution
amount.
18. The method of claim 17, wherein adjusting the engine front-end
airflow based on each of acceleration/deceleration and engine
temperature includes: decreasing the engine front-end airflow in
response to vehicle acceleration event and a coolant temperature
below an upper threshold temperature, increasing the engine
front-end airflow in response to vehicle acceleration event and the
coolant temperature above the upper threshold temperature,
increasing the engine front-end airflow in response to vehicle
deceleration event and the coolant temperature above a lower
threshold temperature, and decreasing the engine front-end airflow
in response to vehicle acceleration and the coolant temperature
below the lower threshold temperature.
19. The method of claim 17, wherein adjusting the engine front-end
airflow based on each of fuel economy, temperature control, and the
oil dilution includes: increasing the engine front-end airflow in
response to vehicle deceleration, coolant temperature above an
upper threshold temperature, and oil dilution above a threshold
amount; increasing the engine front-end airflow in response to
vehicle deceleration, coolant temperature above an upper threshold
temperature, and oil dilution above a threshold amount; decreasing
the engine front-end airflow in response to vehicle deceleration,
coolant temperature below an upper threshold temperature, and oil
dilution above a threshold amount.
20. The method of claim 17, wherein the oil dilution amount is
estimated via intake oxygen sensor measurements during conditions
wherein push-side PCV flow is active.
Description
FIELD
[0001] The present description relates generally to methods and
systems for controlling a vehicle engine.
BACKGROUND/SUMMARY
[0002] Vehicles operating with combustion cylinders may be
configured to inject fuel directly into the fuel chamber. In such a
configuration, fuel injected into the cylinder may impinge on the
cylinder bore walls and accumulate in the oil pan in the crankcase.
If the rate of accumulation exceeds the rate of evaporation of fuel
from the crankcase (e.g., via a positive crankcase ventilation
(PCV) system), the fuel may dilute oil in the oil pan of the
crankcase. Fuel in oil dilution may degrade oil quality, cause fuel
odors in the engine oil, and degrade oxygen intake sensors via
evaporation.
[0003] Other attempts to address fuel in oil dilution include
selectively providing coolant to the engine based on fuel in oil
dilution. One example approach is shown by Takahashi et al. in U.S.
Pat. No. 7,493,883. Therein, a cooling jacket surrounding the
crankcase of the engine is included in the coolant circuit when oil
in fuel dilution is below a threshold level, and is bypassed in the
coolant circuit when oil in fuel dilution is above a threshold
level to raise the temperature of the crankcase and provide greater
fuel vaporization.
[0004] However, the inventors herein have recognized potential
issues with such systems. As one example, fuel economy may be
degraded in instances where the engine is at a high temperature due
to fuel in oil dilution but an acceleration event is commanded. As
a further example, coolant may only be fully provided to the engine
crankcase or absent from the cooling jacket, and not partially
provided to the cooling jacket, providing a less than desired level
of temperature control of the engine crankcase.
[0005] In one example, the issues described above may be addressed
by selectively adjusting a grille shutter opening responsive to
fuel in oil dilution. The adjusting of the grille shutter
responsive to fuel in oil dilution may be in coordination with
adjusting the grille shutter to control coolant temperature and
aerodynamics for maintenance of engine cooling performance and
improved fuel economy, respectively.
[0006] As one example, in response to a fuel in oil dilution level
above an upper threshold, a grille shutter may be adjusted from a
first mid-point position further from the fully closed position to
a second mid-point position closer to the fully closed position.
Temperatures within the engine compartment may then increase, and
more fuel may vaporize out of the oil in the crankcase. In response
to a fuel in oil dilution level returning to below the upper
threshold, a grille shutter may be adjusted from the second
mid-point position to a different position based on one or more of
coolant temperature, charge air cooler temperature, and various
vehicle motion parameters. In this way, fuel in oil dilution may be
improved while still enabling accurate control of coolant
temperature and improving fuel economy.
[0007] It should be understood that the summary above is provided
to introduce in simplified form a selection of concepts that are
further described in the detailed description. It is not meant to
identify key or essential features of the claimed subject matter,
the scope of which is defined uniquely by the claims that follow
the detailed description. Furthermore, the claimed subject matter
is not limited to implementations that solve any disadvantages
noted above or in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 depicts an engine system with adjustable grille
shutters, configured with a turbocharger, direct fuel injectors for
injecting gasoline, positive crankcase ventilation, exhaust gas
recirculation, and fuel vapor purge.
[0009] FIG. 2 depicts a fuel system configured for direct fuel
injection.
[0010] FIG. 3 depicts a flowchart for adjusting a grille shutter
opening based on ECT, acceleration/deceleration, additional engine
operating conditions including CAC temperature, and oil
dilution.
[0011] FIG. 4 depicts a flowchart for estimating an amount of oil
dilution based on one of a PCV fuel compensation strategy and an
oil dilution mode.
[0012] FIG. 5 depicts a flowchart for a PCV fuel compensation
strategy used to estimate an amount of oil dilution based on intake
air oxygen sensor measurements.
[0013] FIG. 6 depicts a flowchart for selectively adjusting a
commanded grille shutter position based on each of ECT and oil
dilution.
[0014] FIG. 7 depicts a flowchart for adjusting a commanded grille
shutter position via a second method.
[0015] FIG. 8 depicts a prophetic sequence of adjusting a grille
shutter opening based on each of ECT and acceleration/deceleration,
and selectively adjusting the opening further based on oil
dilution.
DETAILED DESCRIPTION
[0016] The following description relates to systems and methods for
adjusting a grille shutter opening based on fuel in oil dilution.
FIGS. 1 and 2 depict an example engine system with which these
methods may be executed. FIG. 3 provides a high-order flowchart for
adjusting the grille shutters based on several engine operating
conditions including ECT, acceleration/deceleration, and oil
dilution. Oil dilution may be estimated via the routine provided at
FIG. 4. One method of estimating the oil dilution may include
estimating a dilution amount based on the hydrocarbon content of
the crankcase gases delivered to an intake air oxygen sensor, as
depicted at FIG. 5. FIGS. 6-7 provide two methods for adjusting a
commanded grille shutter position based on an estimated oil
dilution amount, the commanded grille shutter position determined
based on other engine operating conditions. FIG. 8 shows a
graphical example of adjusting grille shutters based on engine
coolant temperature, acceleration/deceleration, and oil dilution
amount.
[0017] FIG. 1 shows an example embodiment of a grille shutter
system 110 and an engine system 100, in a motor vehicle 102,
illustrated schematically. Engine system 100 may be included in a
vehicle such as a road vehicle, among other types of vehicles.
While the example applications of engine system 100 will be
described with reference to a vehicle, it should be appreciated
that various types of engines and vehicle propulsion systems may be
used, including passenger cars, trucks, etc.
[0018] An example configuration of a multi-cylinder engine is
generally depicted at 111, which may be included in a propulsion
system of an automobile. Engine 111 may be controlled at least
partially by a control system 160 of the vehicle including
controller 166 and by input from a vehicle operator 132 via an
input device 130. In this example, input device 130 includes an
accelerator pedal and a pedal position sensor 134 for generating a
proportional pedal position signal PP (not shown).
[0019] In the depicted embodiment, engine 111 is a boosted engine
coupled to a turbocharger including a compressor 50 driven by a
turbine 62. Further, engine 111 is configured to inject fuel from
fuel tank 128 directly into combustion chamber 34 via direct fuel
injector 220. Thus, in examples where the fuel in fuel tank 128 is
gasoline, engine 111 is a gasoline turbocharged direct injection
engine. Specifically, fresh air is introduced along intake passage
12 into engine 111 via air filter 54 and flows to compressor 50.
The compressor may be a suitable intake-air compressor, such as a
motor-driven or driveshaft driven supercharger compressor. In the
engine system 100, the compressor is shown as a turbocharger
compressor mechanically coupled to turbine 62 via a shaft (not
shown), the turbine 62 driven by expanding engine exhaust. In one
embodiment, the compressor and turbine may be coupled within a twin
scroll turbocharger. In another embodiment, the turbocharger may be
a variable geometry turbocharger (VGT), where turbine geometry is
actively varied as a function of engine speed and other operating
conditions. In yet another embodiment, the turbine and compressor
may be included as a supercharger.
[0020] Engine 111 may include a lower portion of the engine block,
indicated generally at 26, which may include a crankcase 28
encasing a crankshaft 30. Crankcase 28 may include an oil sump 32,
otherwise referred to as an oil well, holding engine lubricant
(e.g., oil) positioned below the crankshaft 30. During some
conditions, fuel may enter crankcase 28 via engine cylinders, for
example. An oil fill port 29 may be disposed in crankcase 28 so
that oil may be supplied to oil sump 32. Oil fill port 29 may
include an oil cap 33 to seal oil port 29 when the engine is in
operation. A dip stick tube 37 may also be disposed in crankcase 28
and may include a dipstick 35 for measuring a level of oil in oil
sump 32. In addition, crankcase 28 may include a plurality of other
orifices for servicing components in crankcase 28. These orifices
in crankcase 28 may be maintained closed during engine operation so
that a crankcase ventilation system (described below) may operate
during engine operation. Further, crankcase 28 may include an
air-to-fuel ratio sensor for sensing an air-to-fuel ratio in a
positive crankcase ventilation (PCV) system 16.
[0021] The upper portion of engine block 26 may include a
combustion chamber (e.g., cylinder) 34. The combustion chamber 34
may include combustion chamber walls 36 with piston 38 positioned
therein. Piston 38 may be coupled to crankshaft 30 so that
reciprocating motion of the piston is translated into rotational
motion of the crankshaft. Combustion chamber 34 may receive fuel
from fuel injectors (e.g., direct fuel injector 220) and intake air
from intake manifold 42 which is positioned downstream of throttle
44. The engine block 26 may also include an engine coolant
temperature (ECT) sensor 46 input into a controller 166 (described
in more detail below herein).
[0022] Motor vehicle 102 further includes a grille system 110
including a grille 112 providing an opening (e.g., a grille
opening, a bumper opening, etc.) for receiving ambient air flow 116
through or near the front end of the vehicle and into the engine
compartment. For this reason, ambient air flow 116 is herein also
referred to as an engine front-end airflow. Ambient air flow 116
may then be utilized by radiator 80, engine cooling fan 92, and a
low-temperature radiator (not shown) to keep the engine and/or
transmission cool. The engine cooling fan 92 may be adjusted to
further increase or decrease the air flow to the engine
components.
[0023] Grille shutters 114 may be selectively adjusted to affect
the amount of ambient air flow 116 that is passed through grille
112. As used herein, adjusting grille shutters 114 includes
adjusting the size of a grille shutter opening resultant from the
position or degree of inclination of grille shutters 114. The
position or degree of inclination of grille shutters 114 may be
estimated based on feedback from grille shutter position sensor
118. A grille shutter opening may be a percent of openness from
0-100%, where 0% is completely closed and 100% is completely open.
For example, grille shutters 114 may be adjusted to be completely
shut (0% grille shutter opening) and prevent the flow of air
through grille 112, or may be adjusted to be completely open (100%
grille shutter opening) and allow an unrestricted flow of air
through grille 112. Furthermore, grille shutters 114 may be
adjusted to any one of an infinite number of positions between
completely closed and fully open (corresponding to a grille shutter
opening between 0% and 100%). In this way, an engine front-end
airflow (e.g., ambient airflow 116) may be adjusted by adjusting a
grille shutter position.
[0024] While this example refers to operation of grille shutters,
various other devices may also be used that variably restrict
airflow entering the engine compartment, such as a variable wing or
spoiler, as one example, that can be adjusted to various angles
including mid-point angles between maximum and minimum angle
positions.
[0025] As used herein, the terms "open grille shutter position" and
"open position" refer to a grille shutter position that is more
than half open, or put another way, a grille shutter opening that
is greater than 50%. Similarly, "closed grille shutter position"
and "closed position" refer to a grille shutter position that is
less than half open, or put another way a grille shutter opening
that is less than. Further, a "fully open" or "completely open"
position refers to approximately a 95%-100% grille shutter opening,
while a "fully closed" or "completely closed" position refers to
approximately a 0-5% grille shutter opening. As used herein, a
mid-point opening refers to grille shutter opening between fully
closed (0% open) and fully open (100% open).
[0026] When grille shutters 114 are completely shut, hot air within
the engine compartment may remain in the engine compartment and
contribute to an increase in the ambient temperature within the
engine compartment. When grill shutters 114 are completely open,
ambient air flow 116 may serve to circulate hot air out of the
engine compartment, thereby reducing the ambient temperature within
the engine compartment. Adjusting grille shutters 114 to a degree
of inclination between completely closed and completely open may
result an ambient airflow 116 and an ambient temperature greater
than those that arise when grille shutters 114 are completely open.
In this way, the temperature within engine compartment 102 may be
at least partly controlled by adjusting the degree of inclination
of the grille shutters. Furthermore, as described in further detail
below, a grille shutter opening may be adjusted in response to
various engine operating conditions such as engine speed and load,
vehicle speed, pedal position, conditions of the CAC (CAC
temperature, pressure, and efficiency), engine temperatures, ECT,
fuel in oil dilution level, intake air oxygen content, feedback
grille shutter position, etc., in order to improve one or more of
fuel economy, engine performance, and oil dilution levels. For
example the aerodynamics of vehicle 102 may be improved with a
fully closed grille shutter 114 via a streamlining of the front end
of the vehicle, and therefore during some conditions a fully closed
grille shutter may improve fuel economy.
[0027] In one example, an engine system may detect fuel in oil
dilution in the crankcase (e.g., via operation in combination with
routine 400 at FIG. 4, having corresponding instructions stored in
the memory of controller 166), and in response may adjust a grille
shutter 114 to a more closed position. In one example, the grille
shutter opening may be adjusted to 0%. In another example, if the
grille shutter opening was at 100% or at a mid-point opening, the
grille shutter opening may be adjusted to position closer to 0% but
not fully closed. In this way, ambient temperature may be raised in
the engine compartment and vaporization of fuel within the
crankcase oil may be increased.
[0028] In another example, an engine controller may anticipate an
acceleration event (e.g., from operator 132 via input device 130)
in the near future. In response to an anticipated acceleration
event, the engine controller may adjust the grille shutter opening
to 100%. In another example, if the grille shutter was at 0% or at
an intermediate position, the grille shutter opening may be
adjusted to a position closer to 100% but not fully opening. In
this way, ambient temperature may be decreased in the engine
compartment and overheating of the engine via the anticipated
acceleration may be avoided, thereby improving engine efficiency.
Further examples of adjusting grille shutter responsive to various
engine conditions are discussed with references to FIGS. 3,
6-8.
[0029] Air may enter the engine compartment via grille system 110
and be introduced to fresh air intake passage 12. Fresh air intake
passage 12 may include air filter 54, and may further include a
barometric pressure sensor (BP sensor) 53, upstream of air filter
54, for providing an estimate of barometric pressure (BP), as well
as a compressor inlet pressure (CIP) sensor 58 may be coupled in
intake passage 12 downstream of air filter 54 and upstream of
compressor 50 to provide an estimate of the compressor inlet
pressure (CIP). These sensors may be in electronic communication
with controller 166.
[0030] Engine intake may be in fluid communication with a positive
crankcase ventilation (PCV) system 16, a fuel vapor purge (FVP)
system 17 and an exhaust gas recirculation (EGR) system 18.
Specifically, crankcase ventilation tube 74 of PCV system 16 may be
coupled to intake passage 12 upstream of compressor 50 via a first
end 101 and may be further coupled to crankcase 28 via an oil
separator 81 and a second end 103. Crankcase ventilation tube 74
may couple crankcase 28 to intake passage 12 downstream of air
filter 54 and upstream of compressor 50. During boosted conditions,
gases in the crankcase may be vented from the crankcase through
tube 74 in a controlled manner. In some examples, the gases
delivered from crankcase 28 to intake air passage 12 via tube 74
and first end 101 may include vaporized fuel that had previously
escaped from combustion chamber 34 and diluted into the oil of oil
sump 32. For this reason, crankcase ventilation tube 74 may herein
also be referred to as a push-side conduit or a push-side pipe, and
first end 101 may be referred to herein as a push-side port.
Further, gases traveling in such a manner may be referred to herein
as PCV push-side flow, and push-side PCV flow is said to be
"active" or "present" when gases are flowing from crankcase 28 to
intake air passage 12 via tube push-side conduit 74 and push-side
port 101. However, during non-boosted conditions, a vacuum created
in intake manifold 42 may induce air from intake passage 12 to flow
into crankcase 28 via conduit 74.
[0031] Conduit 76 of PCV system 16 may deliver gases from crankcase
28 to intake manifold 42, downstream of each of compressor 50, IAO2
sensor 88, and throttle 44. During boosted conditions, PCV valve 78
may prevent crankcase gases from flowing through conduit 76 and
into intake manifold 42. However during non-boosted conditions, a
vacuum may be created in intake manifold, and the vacuum may pull
gases from crankcase 28 through conduit 76 and into intake manifold
42 via PCV valve 78 and port 77. For this reason, conduit 76 may
also be referred to herein as a pull-side pipe or a pull-side
conduit, while port 77 may be referred to herein as a pull-side
port. Further, gases traveling in such a manner may be referred to
herein as PCV pull-side flow, and pull-side PCV flow is said to be
"active" or "present" when gases are flowing from crankcase 28 to
intake manifold 42 via tube pull-side conduit 76 and pull-side port
77. In some examples, the gases delivered from crankcase 28 to
intake manifold 42 via pull-side conduit 76 may include vaporized
fuel that had previously escaped from combustion chamber 34 and
diluted into the oil of oil sump 32.
[0032] Fuel vapor purge system 17 may be fluidly connected to
intake air passage 12 upstream of compressor 50 via duct 152 and to
intake manifold 42 downstream of throttle 44 via duct 148, and may
be configured to deliver fuel vapors from fuel tank 128 to each of
intake passage 12 and intake manifold 42. In one example, when FVP
is enabled, fuel vapors may be delivered to the intake system via
duct 152 during boosted conditions, and via duct 148 during
non-boosted conditions. Passage 51 of EGR system 18 may direct
exhaust flow downstream of turbine 62 in exhaust passage 60 back to
intake passage 12, downstream of air filter 54 and upstream of
compressor 50.
[0033] Intake manifold 42 may include pressure sensor 86 for
measuring an intake manifold pressure (MAP). Intake manifold 42
further includes intake air oxygen (IAO2) sensor 88 for measuring
an oxygen content of air entering cylinder 34. IAO2 sensor 88 may
be one of a linear oxygen sensor universal or wide-range oxygen
sensor, a two-state oxygen sensor, and a heated oxygen sensor. IAO2
sensor 88 may be positioned downstream of each of the fluid
connections to the FVP and EGR systems 17 and 18, and upstream of
intake valve 31 such that oxygen content is measured after all
effluents have been introduced to the intake stream. Further, IAO2
sensor may be positioned downstream of push-side conduit 74 but
upstream of pull-side conduit 76. During some conditions, when EGR
and fuel vapor purge are inactive and push-side PCV flow is active
(e.g., during boosted conditions), measurements from IAO2 sensor 88
may be used to determine a hydrocarbon (HC) concentration of gases
from crankcase 28. During other conditions, measurements from IAO2
sensor 88 may be used to determine an amount of recirculated
exhaust gas to introduce to intake manifold 42 via EGR system
18.
[0034] As shown in FIG. 1, compressor 50 is coupled to charge air
cooler (CAC) 52. In an alternate embodiment, the throttle 44 may be
coupled to the engine intake manifold 42, downstream of the CAC 52.
From the compressor, the hot compressed air charge enters the inlet
of the CAC 52, cools as it travels through the CAC, passes through
the throttle valve 44, and then exits toward the intake manifold
42. In the embodiment shown in FIG. 1, the CAC 52 is a water-to-air
heat exchanger. As such, CAC 52 comprises a series of coolant tubes
which water or coolant may flow through to cool the charge air
passing over the outside of the coolant tubes. The coolant tubes of
CAC 52 may be connected to a low-temperature radiator circuit (not
shown). The low-temperature radiator circuit may include a
low-temperature radiator, coolant tubing, and a coolant pump (not
shown). The low-temperature radiator may cool warmed coolant
flowing from the CAC 52. As such, the coolant pump may pump cooled
coolant from the low-temperature radiator, through the coolant
tubing, and to the CAC 52. Coolant then flows through the coolant
tubes of the CAC 52, thereby cooling warmer charge air passing
through the CAC 52. As the coolant travels through the CAC, the
temperature of the coolant may increase. Warmed coolant may then
travel from the CAC 52 back to the low-temperature radiator to be
cooled again.
[0035] A throttle 44 may be disposed in intake passage 12 to
control the airflow entering intake manifold 42 and may be preceded
upstream by compressor 50 followed by charge air cooler 52, for
example. Compressor 50 may compress the intake air to engine 111,
thereby boosting intake air pressure and density providing boosted
engine conditions (e.g., manifold air pressure >barometric
pressure), for example during increased engine loads. An air filter
54 may be positioned upstream compressor 50 and may filter fresh
air entering intake passage 12. In the depicted example, throttle
44 is positioned upstream of PCV pull-side port 77 and FVP duct
148, and downstream of each of PCV push-side port 101, EGR passage
51, FVP duct 152, compressor 50, CAC 52, and IAO2 sensor 88.
[0036] Intake manifold 42 is coupled to a series of combustion
chambers 34 through a series of intake valves 31. It will be
understood that although as depicted in FIG. 1, intake manifold 42
comprises only one section delivering effluent to only one
combustion chamber 34, engine 111 may comprise multiple combustion
chambers 34, only one of which is shown, and intake manifold 42 may
comprise a plurality of intake manifold sections to deliver
effluent from a common intake passage to the plurality of
combustion chambers 34. The combustion chambers are further coupled
to exhaust manifold 60 via a series of exhaust valves 39. In the
depicted embodiment, a single exhaust manifold 60 is shown.
However, in other embodiments, exhaust manifold 60 may include a
plurality of exhaust manifold sections. Configurations having a
plurality of exhaust manifold section may enable effluent from
different combustion chambers to be directed to different locations
in the engine system. Universal Exhaust Gas Oxygen (UEGO) sensor 64
is shown coupled to exhaust manifold 60 upstream of turbine 62.
Alternatively, a two-state exhaust gas oxygen sensor may be
substituted for UEGO sensor 64.
[0037] In the example of FIG. 1, a positive crankcase ventilation
system (PCV) 16 is coupled to the engine fresh air intake 12 so
that gases in the crankcase 28 may be vented in a controlled
manner. During normal engine operation, gases in the combustion
chamber 34 may escape past the piston. These blow-by gases may
include unburned fuel, combustion products, and air. Blow-by gases
can dilute and contaminate oil, causing corrosion to engine
components and contributing to sludge build-up, reducing the
protective and lubricating properties of the oil. At higher engine
speeds, blow-by gases can increase crankcase pressure such that oil
leakage may occur from sealed engine surfaces. The PCV system 16
may help to vent and remove blow-by gases from the engine crankcase
in a controlled manner in order to mitigate these harmful effects
of blow-by gases and may combine them with an engine intake stream
so that they may be combusted within the engine. By redirecting
blow-by gases to the engine intake, the PCV system 16 further aids
in reducing engine emissions by precluding venting of blow-by gases
to the atmosphere.
[0038] In one example, PCV system 16 may help to remove fuel in oil
dilution of oil in engine crankcase 28. Specifically, when engine
temperatures are above a threshold temperature, fuel diluted in
crankcase oil may vaporize out of solution and instead may
partially compose the blow-by gas ventilated by PCV system. The
amount of vaporized fuel may increase with increased temperature.
Thus, by increasing engine temperatures, for example by closing
grille shutters 114 of engine system 100, more vaporized fuel may
compose the blow-by gas of crankcase 28 and be ventilated out of
crankcase, thereby reducing a fuel in oil dilution of oil in the
crankcase. In this way, oil dilution may be improved during
conditions where the PCV system is active.
[0039] The PCV system 16 includes a PCV valve 78 fluidly coupled to
engine crankcase 28. As an example, the PCV valve 78 may be coupled
to a valve cover in the engine, which may allow for the PCV system
to draw blow-by gases from the engine while reducing the
entrainment of oil from the crankcase. The PCV valve 78 may also be
fluidly coupled to the engine intake manifold 42. The PCV valve gas
flow rate may vary with engine conditions such as engine speed and
load, and the PCV valve 78 may be calibrated for a particular
engine application wherein the PCV valve gas flow rate may be
adjusted as operating conditions change. As an example, when the
engine is off, the PCV valve may be closed and no gases may flow
through the PCV valve 78. When the engine speed is idling or low,
or during deceleration when the intake manifold vacuum is
relatively high, the PCV valve 78 may open slightly, allowing for
restricted PCV valve gas flow rates. At engine speeds or loads
higher than idling, intake manifold vacuum may lower, and the PCV
valve 78 may allow for higher PCV valve gas flow rates. PCV valve
78 may include a conventional PCV valve or a push-pull type PCV
valve. As one example, PCV valve 78 may be a check valve.
[0040] In some embodiments, crankcase ventilation tube 74 may
include a pressure sensor 61 coupled therein. Pressure sensor 61
may be an absolute pressure sensor or a gauge sensor. One or more
additional pressure and/or flow sensors may be coupled to the PCV
system 16 at alternate locations. In one example, pressure sensor
61 may be configured as a gauge sensor, and barometric pressure
sensor 58, coupled to intake passage 12 upstream of air filter 54,
may be used in conjunction with pressure sensor 61. In some
embodiments, a compressor inlet pressure (CIP) sensor 58 may be
coupled in intake passage 12 downstream of air filter 54 and
upstream of compressor 50 to provide an estimate of the compressor
inlet pressure (CIP).
[0041] While the engine is running under light load and moderate
throttle opening, such as during non-boosted conditions, the intake
manifold air pressure may be less than crankcase air pressure. The
lower pressure of the intake manifold 42 draws fresh air towards
it, pulling air from the push-side conduit 74 through the crankcase
(where it dilutes and mixes with combustion gases), out of the
crankcase via the pull-side conduit 76 through the PCV valve 78,
and into the intake manifold 42. However, during other conditions,
such as heavy load or under boosted conditions, the intake manifold
air pressure may be greater than crankcase air pressure. As such,
intake air may travel through the PCV conduit 76 and into the
crankcase 28.
[0042] Specifically, during non-boosted conditions (when intake
manifold pressure (MAP) is less than barometric pressure (BP)), the
PCV system 16 draws air into crankcase 28 via a breather or
crankcase ventilation (vent) tube 74. A first end 101 of crankcase
ventilation tube 74 may be mechanically coupled, or connected, to
fresh air intake 12 upstream of compressor 50. In some examples,
the first end 101 of crankcase ventilation tube 74 may be coupled
to fresh air intake 12 downstream of air filter 54 (as shown). In
other examples, the crankcase ventilation tube may be coupled to
fresh air intake 12 upstream of air filter 54. In yet another
example, the crankcase ventilation tube may be coupled to air
filter 54. A second end 102, opposite first end 101, of crankcase
ventilation tube 74 may be mechanically coupled, or connected, to
crankcase 28 via an oil separator 81.
[0043] Still during non-boosted conditions, PCV system 16 may vent
air out of crankcase 28 and into intake manifold 42 via pull-flow
conduit 76 which, in some examples, may include a one-way PCV valve
78 to provide continual evacuation of gases from inside the
crankcase 28 before connecting to the intake manifold 42. In one
embodiment, the PCV valve 78 may vary its flow restriction in
response to the pressure drop across it (or flow rate through it).
However, in other examples conduit 76 may not include a one-way PCV
valve. In still other examples, the PCV valve may be an
electronically controlled valve that is controlled by controller
166. It will be appreciated that, as used herein, pull-side PCV
flow refers to the flow of gases through conduit 76 and pull-side
port 77 from the crankcase to the intake manifold 42. As an
example, the pull-side PCV flow may be determined from the fuel
(e.g., gaseous fuel) injection rate, the air/fuel ratio in the
engine intake, and the exhaust oxygen content via exhaust gas
sensor 64, using known methods.
[0044] As used herein, PCV backflow refers to the flow of gases
through pull-side conduit 76 from the intake manifold 42 to the
crankcase 28. PCV backflow may occur when intake manifold pressure
is higher than crankcase pressure (e.g., during boosted engine
operation). In some examples (such as the depicted example), PCV
system 16 may be equipped with a check valve for preventing PCV
backflow. It will be appreciated that while the depicted example
shows PCV valve 78 as a passive valve, this is not meant to be
limiting, and in alternate embodiments, PCV valve 78 may be an
electronically controlled valve (e.g., a powertrain control module
(PCM) controlled valve) wherein a controller 166 of control system
160 may command a signal to change a position of the valve from an
open position (or a position of high flow) to a closed position (or
a position of low flow), or vice versa, or any position
there-between.
[0045] During boosted conditions (when MAP is greater than BP),
gases flow from the crankcase, through oil separator 81 and
push-side conduit 74, and into fresh air intake 12 and eventually
into the combustion chamber 34. This may be done in a stale air
manner where no intake manifold air is let into the crankcase 28 or
in a positive crankcase ventilation manner where some manifold air
is metered into the crankcase 28. The flow of gases from the
crankcase through the push-side conduit 74, and into intake passage
12 via push-side port 101 is also referred to herein as push-side
PCV flow or PCV push-side flow.
[0046] The gases in crankcase 28 may include un-burned fuel,
un-combusted air, and fully or partially combusted gases. Further,
lubricant mist may also be present. As such, various oil separators
may be incorporated in positive PCV system 16 to reduce exiting of
the oil mist while allowing exiting of fuel vapor from the
crankcase 28 through the PCV system 16. For example, conduit 76 may
include a uni-directional oil separator 82 which filters oil from
vapors exiting crankcase 28 before they re-enter the intake
manifold 42. Another oil separator 81 may be disposed in crankcase
ventilation tube 74 to remove oil from the stream of gases exiting
the crankcases during boosted operation. Additionally, in some
embodiments, conduit 76 may also include a vacuum sensor 84 coupled
to the PCV system 16.
[0047] Exhaust combustion gases exit the combustion chamber 34 via
exhaust passage 60 located upstream of turbine 62. An exhaust gas
sensor 64 may be disposed along exhaust passage 60 upstream of
turbine 62. Turbine 62 may be equipped with a wastegate bypassing
it (not shown), and turbine 62 may be driven by the flow of exhaust
gases passing there through. Furthermore, turbine 62 may be
mechanically coupled to compressor 50 via a common shaft (not
shown), such that rotation of turbine 62 may drive compressor 50.
Sensor 64 may be a suitable sensor for providing an indication of
engine air-to-fuel ratio from exhaust gas constituents. For
example, sensor 64 may be a linear oxygen sensor or UEGO (universal
or wide-range exhaust gas oxygen), a two-state oxygen sensor or
EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. Exhaust gas
sensor 64 may be in electrical communication with controller 166.
As discussed herein, the engine air-to-fuel ratio may be utilized
to estimate an oil dilution amount.
[0048] All or part of the treated exhaust from emission control
device 69 may be released into the atmosphere via exhaust conduit
70. Depending on operating conditions, however, some exhaust may be
diverted instead to EGR passage 51, through EGR cooler 47 and EGR
valve 49, to the inlet of compressor 50. In this manner, the
compressor is configured to admit exhaust tapped from downstream of
turbine 62. The EGR valve may be opened to admit a controlled
amount of cooled exhaust gas to the compressor inlet for desirable
combustion and emissions-control performance. In this way, engine
system 100 is adapted to provide external, low-pressure (LP) EGR.
The rotation of the compressor, in addition to the relatively long
LP EGR flow path in engine system 100, provides excellent
homogenization of the exhaust gas into the intake air charge.
Further, the disposition of EGR take-off and mixing points provides
effective cooling of the exhaust gas for increased available EGR
mass and improved performance.
[0049] In some examples, EGR system 18 may further include a
differential pressure over valve (DPOV) sensor (not pictured). In
one example, an EGR flow rate may be estimated based on the DPOV
system which includes the DPOV sensor that detects a pressure
difference between an upstream region of the EGR valve 49 and a
downstream region of EGR valve 49. This EGR flow rate may be used
in part to determine the contribution of EGR gases to measurements
of intake air oxygen content as measured by IAO2 sensor 88.
[0050] Fuel system 19 may include a fuel tank 128 coupled to a fuel
pump system 202. The fuel pump system 202 may include one or more
pumps for pressurizing fuel delivered to the injectors of engine
111, such as the example direct fuel injector 220 shown. While only
a single fuel injector 220 is shown, additional fuel injectors may
be provided for each cylinder, for instance port fuel injector 221
at FIG. 2. It will be appreciated that fuel system 19 may be a
return-less fuel system, a return fuel system, or various other
types of fuel system. Vapors generated in fuel system 19 may be
routed to a fuel vapor canister 104, described further below, via
conduit 135, before being purged via fuel vapor purging system 17.
Conduit 135 may optionally include a fuel tank isolation valve.
Among other functions, fuel tank isolation valve may allow the fuel
vapor canister 104 to be maintained at a low pressure or vacuum
without increasing the fuel evaporation rate from the tank (which
would otherwise occur if the fuel tank pressure were lowered). The
fuel tank 128 may hold a plurality of fuel blends, including fuel
with a range of alcohol concentrations, such as various
gasoline-ethanol blends, including E10, E85, gasoline, etc., and
combinations thereof.
[0051] Fuel vapor canister 104 may be filled with an appropriate
adsorbent and configured to temporarily trap fuel vapors (including
vaporized hydrocarbons) during fuel tank refilling operations and
"running loss" (that is, fuel vaporized during vehicle operation).
In one example, the adsorbent used is activated charcoal. Fuel
vapor canister 104 may further include a vent 136 which may route
gases out of the canister 104 to the atmosphere when storing, or
trapping, fuel vapors from fuel system 19. Vent 136 may also allow
fresh air to be drawn into fuel vapor canister 104 when purging
stored fuel vapors from fuel system 19 to intake 12 via fuel vapor
purging system 17. While this example shows vent 136 communicating
with fresh, unheated air, various modifications may also be used.
Flow of air and vapors between fuel vapor canister 104 and the
atmosphere may be regulated by the operation of a canister vent
solenoid (not shown), coupled to canister vent valve 172.
[0052] Fuel vapor canister 104 operates to store vaporized
hydrocarbons (HCs) from fuel system 19. Under some operating
conditions, such as during refueling, fuel vapors present in the
fuel tank may be displaced when liquid is added to the tank. The
displaced air and/or fuel vapors may be routed from the fuel tank
128 to the fuel vapor canister 104, and then to the atmosphere
through vent 136. In this way, an increased amount of vaporized HCs
may be stored in fuel vapor canister 104.
[0053] During a later engine operation, the stored vapors may be
released back into the incoming air charge via fuel vapor purging
system 17. Fuel vapor purging system 17 includes ejector 140, which
includes a housing 168. One or more check valves may be arranged
within housing 168. Further, ejector 140 includes a first port 142,
a second port 144, and a third port 146. In one example, only these
three ports are included. Duct 148 couples first port 142 of
ejector 140 to intake passage 12 downstream of each of compressor
50 and throttle 44. Duct 150 couples second port 144 of ejector 140
to fuel vapor canister 104. Duct 152 couples third port 146 of
ejector 140 to intake passage 12 upstream of compressor 50 (i.e.,
at an upstream inlet of the compressor). Duct 152 may be coupled to
intake passage 12 downstream of an air filter 54. A CPV 158 is
arranged in duct 150, to regulate the flow of vapors from fuel
vapor canister 104 to ejector 140. Optionally, a third check valve
170 may be included in duct 148 intermediate the ejector and the
intake passage. The ejector is designed such that during boost
conditions, a low pressure zone is created in the ejector which
draws fuel vapors from the CPV to the upstream inlet of the
compressor. Under vacuum conditions, for example when intake
manifold vacuum is present, fuel vapors are drawn from the CPV,
through the ejector, to the intake manifold.
[0054] It should be appreciated that fuel vapor canister 104 is not
coupled directly to intake passage 12 or intake manifold 42.
Rather, the canister is coupled to ejector 140 via duct 150, and
ejector 140 is coupled to intake passage 12 upstream of compressor
50 via duct 152 and to intake passage 12 downstream of throttle 44
via duct 148. Further, it should be appreciated that fuel vapor
canister 104 is coupled (via duct 150 and ejector 140) to intake
passage 12 downstream of the throttle, and not upstream of the
throttle. In this way, vapor flow from fuel vapor canister 104
passes through second port 144 of ejector 140 before continuing on
to the intake passage via third port 146 or first port 142 of the
ejector, depending on whether boost or vacuum conditions are
present.
[0055] The vehicle system 100 may further include control system
160. Control system 160 is shown receiving information from a
plurality of sensors 162 and sending control signals to a plurality
of actuators 164. Sensors 162 may include pressure, temperature,
air/fuel ratio, and composition sensors, for example. Actuators 164
may include fuel injector 132, CPV 158, throttle 44, and a grille
shutter actuator (not shown), for example. The control system 160
may include a controller 166. The controller may receive input data
from various sensors, process the input data, and trigger various
actuators in response to the processed input data based on
instruction or code programmed therein corresponding to one or more
routines. For example, as detailed below with respect to FIG. 3,
the controller may determine a desired angle of inclination for
grille shutters 114 based on engine operating conditions.
[0056] Turning now to FIG. 2, it shows a direct injection fuel
system 200 coupled to an internal combustion engine 210, which may
be configured as a propulsion system for a vehicle. The internal
combustion engine 210 may comprise multiple combustion chambers or
cylinders 34. LPG fuel can be provided directly to the cylinders 34
via in-cylinder direct injectors 220. As indicated schematically in
FIG. 2, the engine 210 can receive intake air and it can exhaust
products of the combusted fuel and air.
[0057] Fuel can be provided to the engine 210 via the injectors 220
by way of a fuel pump system indicated generally at 202. In this
particular example, the fuel pump system 202 includes a fuel
storage tank 128 for storing the fuel on-board the vehicle, a lower
pressure fuel pump 230 (e.g., a fuel lift pump), a higher pressure
fuel pump or direct injection fuel pump 240, a fuel rail 258, and
various fuel passages 254, 255, and 256. In the example shown in
FIG. 2, the fuel passage 254 carries fuel from the lower pressure
pump 230 to the fuel filter 206. Fuel passage 255 carries fuel from
fuel filter 206 to fuel cooling chamber 237 before fuel reaches
direct injection fuel pump 240. Fuel passage 256 carries fuel from
the fuel injection pump 240 to the fuel rail 258.
[0058] Fuel cooling chamber 237 includes a fuel injector 223 that
is supplied fuel from fuel passage 255. Fuel injector 223 may
inject fuel into fuel cooling chamber 237 where the pressurized
fuel expands to vapor and cools liquid fuel flowing into direct
injection fuel pump 240. Expanded fuel may be injected to engine
210 via a port fuel injector 221 which injects vaporized fuel into
the engine intake manifold or cylinder intake runners.
Alternatively, expanded fuel may exit fuel cooling chamber 237 and
be returned to fuel tank 252 via passage 233. Fuel injector 223 is
opened and closed via a pulse width modulated voltage supplied by
controller 270. This gaseous fuel may also be routed to the fuel
vapor purge system which is in place for the gasoline fuel system,
if the vehicle is equipped with an auxiliary gasoline system.
[0059] Fuel rail 258 may distribute fuel to each of a plurality of
fuel injectors 220. Each of the plurality of fuel injectors 220 may
be positioned in a corresponding cylinder 34 of engine 210 such
that during operation of fuel injectors 220 fuel is injected
directly into each corresponding cylinder 34. Alternatively (or in
addition), engine 210 may include fuel injectors positioned at the
intake port of each cylinder such that during operation of the fuel
injectors fuel is injected in to the intake port of each cylinder.
In the illustrated example, engine 210 includes four cylinders.
However, it will be appreciated that the engine may include a
different number of cylinders.
[0060] The lower pressure fuel pump 230 can be operated by a
controller 270 to provide fuel to fuel injection pump 240 via fuel
passage 254. The lower pressure fuel pump 230 can be configured as
what may be referred to as a fuel lift pump. As one example, lower
pressure fuel pump 230 can include an electric pump motor, whereby
the pressure increase across the pump and/or the volumetric flow
rate through the pump may be controlled by varying the electrical
power provided to the pump motor, thereby increasing or decreasing
the motor speed. For example, as the controller 270 reduces the
electrical power that is provided to pump 230, the volumetric flow
rate and/or pressure increase across the pump 230 may be reduced.
The volumetric flow rate and/or pressure increase across the pump
may be increased by increasing the electrical power that is
provided to the pump 230. As one example, the electrical power
supplied to the lower pressure pump motor can be obtained from an
alternator or other energy storage device on-board the vehicle (not
shown), whereby the control system can control the electrical load
that is used to power the lower pressure pump 230. Thus, by varying
the voltage and/or current provided to the lower pressure fuel pump
230 via conductor 282, the flow rate and pressure of the fuel
provided to fuel injection pump 240 and ultimately to the fuel rail
may be adjusted by the controller 270.
[0061] Low-pressure fuel pump 230 may be in fluid communication
with check valve 204 to facilitate fuel delivery, prevent fuel
backflow, and maintain fuel line pressure. In particular, check
valve 204 includes a ball and spring mechanism that seats and seals
at a specified pressure differential to deliver fuel downstream of
check valve 204. In some examples, fuel system 250 may include a
series of check valves in fluid communication with low-pressure
fuel pump 230 to further impede fuel from leaking back upstream of
the valves. Check valve 204 is in fluid communication with fuel
filter 206. Fuel filter 206 may remove small impurities that may be
contained in the fuel that could potentially restrict fuel flow.
Fuel may be delivered from filter 206 to fuel injector 223 and
high-pressure fuel pump (e.g., fuel injection pump) 240. Fuel
injection pump 240 may increase the pressure of fuel received from
the fuel filter from a first pressure level generated by
low-pressure fuel pump 230 to a second pressure level higher than
the first level. Fuel injection pump 240 may deliver high pressure
fuel to fuel rail 258 via fuel line 256. Operation of direct
injection fuel pump 240 may be adjusted based on operating
conditions of the vehicle in order to reduce
noise/vibration/harshness (NVH) which may be perceived positively
by a vehicle operator.
[0062] The direct injection fuel pump 240 can be controlled by the
controller 270 to provide fuel to the fuel rail 258 via the fuel
passage 256. As one non-limiting example, fuel injection pump 240
may utilize a flow control valve, a solenoid actuated "spill valve"
(SV) or fuel volume regulator (FVR), indicated at 242 to enable the
control system to vary the effective pump volume of each pump
stroke. The fuel injection pump 240 may be mechanically driven by
the engine 210 in contrast to the motor driven lower pressure fuel
pump or fuel lift pump 230. A pump piston 244 of the direct
injection fuel pump 240 can receive a mechanical input from the
engine crank shaft or cam shaft via a cam 246. In this manner, fuel
injection pump 240 can be operated according to the principle of a
cam-driven single-cylinder pump.
[0063] As depicted in FIG. 2, a fuel sensor 248 is disposed in
passage 254 downstream of the fuel lift pump 230. The fuel sensor
248 may measure fuel composition and may operate based on fuel
capacitance, or the number of moles of a dielectric fluid within
its sensing volume. For example, an amount of ethanol (e.g., liquid
ethanol) in the fuel may be determined (e.g., when a fuel alcohol
blend is utilized) based on the capacitance of the fuel. The fuel
sensor 248 may be used to determine a level of vaporization of the
fuel, as fuel vapor has a smaller number of moles within the
sensing volume than liquid fuel. As such, fuel vaporization may be
indicated when the fuel capacitance drops off. As described in
greater detail with reference to FIGS. 4 and 5, the fuel sensor 248
may be utilized to determine the level of fuel vaporization of the
fuel such that the controller 270 may adjust the lift pump output
pressure in order to reduce fuel vaporization within the fuel lift
pump 230.
[0064] Further, in some examples, the direct injection fuel pump
240 may be operated as the fuel sensor 248 to determine the level
of fuel vaporization. For example, a piston-cylinder assembly of
the fuel injection pump 240 forms a fluid-filled capacitor. As
such, the piston-cylinder assembly allows the fuel injection pump
240 to be the capacitive element in the fuel composition sensor. In
some examples, the piston-cylinder assembly of the fuel injection
pump 240 may be the warmest point in the system, such that fuel
vapor forms there first. In such an example, the direct injection
fuel pump 240 may be utilized as the sensor for detecting fuel
vaporization, as fuel vaporization may occur at the piston-cylinder
assembly before it occurs anywhere else in the system.
[0065] As shown in FIG. 2, the fuel rail 258 includes a fuel rail
pressure sensor 262 for providing an indication of fuel rail
pressure to the controller 270. An engine speed sensor 264 can be
used to provide an indication of engine speed to the controller
270. The indication of engine speed can be used to identify the
speed of fuel injection pump 240, since the pump 240 is
mechanically driven by the engine 210, for example, via the
crankshaft or camshaft. An exhaust gas sensor 266 can be used to
provide an indication of exhaust gas composition to the controller
270. As one example, the gas sensor 266 may include a universal
exhaust gas sensor (UEGO). The exhaust gas sensor 266 can be used
as feedback by the controller to adjust the amount of fuel that is
delivered to the engine via the injectors 220. In this way, the
controller 270 can control the air-fuel ratio delivered to the
engine to a desired air-fuel ratio.
[0066] Furthermore, controller 270 may receive other engine/exhaust
parameter signals from other engine sensors such as engine coolant
temperature, engine speed, throttle position, absolute manifold
pressure, emission control device temperature, etc. Further still,
controller 270 may provide feedback control based on signals
received from fuel sensor 248, pressure sensor 262, and engine
speed sensor 264, among others. For example, controller 270 may
send signals to adjust a current level, current ramp rate, pulse
width of a solenoid valve (SV) 242 of fuel injection pump 240, and
the like to adjust operation of fuel injection pump 240, a fuel
pressure set-point of fuel pressure regulator, and/or a fuel
injection amount and/or timing based on signals from fuel sensor
248, pressure sensor 262, engine speed sensor 264, and the
like.
[0067] The controller 270 can individually actuate each of the
injectors 220 and injector 223. The controller 270 and other
suitable engine system controllers can comprise a control system.
The controller 270, in this particular example, includes an
electronic control unit comprising one or more of an input/output
device 272, a central processing unit (CPU) 274, read-only memory
(ROM) 276 or non-transitory memory, random-accessible memory (RAM)
277, and keep-alive memory (KAM) 278. The storage medium ROM 276
can be programmed with computer readable data representing
non-transitory instructions executable by the processor 274 for
performing the methods described below as well as other variants
that are anticipated but not specifically listed.
[0068] As shown, direct injection fuel system 200 is a returnless
fuel system, and may be a mechanical returnless fuel system (MRFS)
or an electronic returnless fuel system (ERFS). In the case of an
MRFS, the fuel rail pressure may be controlled via a pressure
regulator (not shown) positioned at the fuel tank 128. In an ERFS,
a pressure sensor 262 may be mounted at the fuel rail 258 to
measure the fuel rail pressure relative to the manifold pressure.
The signal from the pressure sensor 262 may be fed back to the
controller 270 which modulates the voltage to the fuel injection
pump 240 for supplying the desired fuel pressure and fuel flow rate
to the injectors.
[0069] Although not shown in FIG. 2, in other examples, direct
injection fuel system 200 may include a return line whereby excess
fuel from the engine is returned via a fuel pressure regulator to
the fuel tank via a return line. A fuel pressure regulator may be
coupled in line with a return line to regulate fuel delivered to
fuel rail 258 at a desired pressure. To regulate the fuel pressure
at the desired level, the fuel pressure regulator may return excess
fuel to fuel tank 128 via the return line. It will be appreciated
that operation of fuel pressure regulator may be adjusted to change
the desired fuel pressure to accommodate operating conditions.
[0070] FIG. 3 provides an example routine 300 for determining a
desired grille shutter opening (e.g., the opening of grille
shutters 114 at FIG. 1) based on various engine operating
conditions and commanding an adjustment of the grille shutter
opening to a commanded position, the commanded position determined
based on the desired position. In this way, an engine front-end
airflow may be adjusted. In some examples, the desired and
commanded grille shutter positions may be restricted to be one of
fully open or fully closed. However in other examples, the desired
and commanded grille shutter positions may further a mid-point
position between fully open and fully closed.
[0071] The commanded position may differ from the desired position
in instances where multiple engine conditions which correspond to
differing desired positions are present. For instance, a first
engine condition may be present which corresponds to a fully closed
position, while a second engine condition may be present which
corresponds to a fully open grille shutter position. In this
example, the commanded position may be an intermediate position
between fully closed and fully open. In the depicted embodiment,
desired and commanded grille shutter positions are determined based
on each of engine coolant temperature and vehicle acceleration,
then selectively adjusted further based on an estimated fuel-in-oil
dilution level.
[0072] Routine 300 beings by estimating and/or measuring engine
operating conditions. Engine operating conditions may include
engine speed and load, vehicle speed, pedal position, conditions of
the CAC (CAC temperature and pressure), CAC efficiency, engine
temperatures, ECT, feedback grille shutter position, etc. At 304,
the method includes determining if ECT is greater than an upper
threshold temperature. The threshold temperature may be based on an
ECT indicating a need for increased cooling of the radiator and
additional engine components. If the ECT is not greater than the
upper threshold temperature, routine 300 continues to 306.
[0073] Alternatively at 304, if ECT is greater than the threshold
temperature, routine 300 continues to 308 where the controller
determines the desired and corresponding commanded grille shutter
position based on ECT and independent of additional engine
operation conditions. In the depicted example, determining the
desired and commanded positions based only on ECT includes choosing
the desired and commanded positions to be fully open responsive to
ECT above the upper threshold temperature. In an alternate
embodiment, the desired and commanded positions may be chosen to be
open mid-point positions more open than the current grille shutter
position, thereby increasing engine front-end airflow. In this way,
engine front-end airflow may be increased in response to coolant
temperature above the upper threshold temperature, thereby
providing more ventilation to the engine compartment and reducing
engine temperatures.
[0074] In further example, at 308, the desired grille shutter
position may be a function of ECT only and the corresponding
commanded grille shutter position may be based on the desired
grille shutter position and vehicle speed. In a further example,
the desired and/or commanded grille shutter position may a function
of ECT starting from a base percentage opening. The base percentage
opening may be a partially open position. As one example, the base
percentage opening may be 10%. In another example, the base
percentage opening may be greater than 0% and smaller or greater
than 10%. In this way, the controller may open the grille shutters
to at least the base opening when the ECT is greater than the
threshold.
[0075] Continuing at 306, the controller may determine whether
vehicle acceleration was detected at 302. In one example, the
acceleration event may be detected via a pedal position signal from
a pedal position sensor (e.g., pedal position sensor 134 at FIG. 1)
or in another example via an accelerometer. If vehicle acceleration
is detected, and the engine coolant temperature is not above an
upper threshold temperature (note this second condition was
confirmed at 304), routine 300 proceeds to 310. At 310 the desired
and commanded positions are chosen as fully closed. In an alternate
embodiment, the desired and commanded positions may be chosen as
closed mid-point positions more closed than the current grille
shutter position, thereby decreasing front-end engine airflow. In
this way, if coolant temperature does not indicate overheating,
fuel economy may be improved during vehicle acceleration via
improved aerodynamics. After choosing the commanded position as
fully closed, routine 300 proceeds to 318.
[0076] At 312, the controller may determine the desired and
corresponding commanded grille shutter position based on ECT and
additional engine operation conditions not including oil dilution.
The additional engine operating conditions may include one or more
of driving conditions, deceleration, CAC efficiency, CAC
condensation level, vehicle speed, etc. The desired grille shutter
position may be fully open in response to a deceleration event. The
desired and commanded grille shutter position may be fully closed
in response to engine coolant temperature below a lower threshold
temperature.
[0077] In some examples, determining desired and commanded grille
shutter positions may be based only on engine coolant temperature.
In other examples, determining desired and commanded grille shutter
positions may be based on each of engine coolant temperature and
vehicle acceleration/deceleration. Further, during conditions where
neither of vehicle acceleration or deceleration is present,
determining the desired and commanded grille shutter positions
based on engine coolant temperature and vehicle
acceleration/deceleration at 312 may comprise determining the
desired and commanded grille shutter positions based only on engine
coolant temperature. In a further example, determining the
commanded position at 312 may be based on a weighted average of
desired positions associated with various engine operating
conditions.
[0078] At 314, an amount of fuel diluted in the crankcase oil
supply (e.g., fuel diluted in oil sump 32 at FIG. 1), herein also
referred to as an oil dilution amount and as a fuel in oil dilution
level, is estimated. In one example, the fuel in oil dilution level
may be estimated via routine 400 at FIG. 4. Therein, as described
in further detail below, one of an oil dilution model and a PCV
fuel compensation strategy may be used to estimate an oil dilution
amount. At 315, the estimated oil dilution amount may be compared
to a threshold dilution amount and the desired grille shutter
position may be selectively adjusted based on this comparison. In
one example, the threshold may be based on a number of cold start
operations without warm-up, the estimated dilution, and an
estimated hot cycle dilution at shutdown. In another example, the
threshold may be determined based on the temperature of the oil at
the last engine shut down command, which may provide an indication
of the amount of accumulated fuel accumulated in previous vehicle
trips.
[0079] At 316, a decision is made based on the comparison made at
315. Specifically, if the fuel in oil dilution level is below the
threshold dilution level, routine 300 proceeds directly to 320 to
adjust the grille shutter to the commanded position as determined
at 312 independent of an estimated fuel in oil dilution level.
Alternatively, if the oil dilution level is above the threshold
level, the desired grille shutter position may be adjusted from the
position determined at 312 to a commanded position further based on
estimated fuel in oil dilution level. In one example, the commanded
position may be adjusted based on a desired grille shutter position
corresponding to the estimated oil dilution amount. In another
example, the commanded position may be adjusted to be the desired
position corresponding to the estimated oil dilution amount.
Adjusting the commanded grille shutter opening based on the
estimated oil dilution amount may be performed via one of routines
600 and 700 and is discussed with further detail with reference to
FIGS. 6-7. After further adjusting the commanded grille shutter
position based on an estimated oil dilution amount at 318, routine
300 proceeds to 320 to adjust the grille shutter to the commanded
position.
[0080] At 320, routine 300 adjusts the grille shutter to the
commanded grille shutter position, for example via a grille shutter
actuator. In one example, adjusting the grille shutter opening
includes adjusting an angle of opening from a first mid-point
position to a second, different, mid-point position. Adjusting the
grille shutter to the commanded position may include adjusting the
grille shutter to the commanded position and maintaining the grille
shutter at the commanded position or a specified duration, the
duration determined based on an estimated rate of temperature
increase for at one or more of engine oil and engine coolant.
Adjusting the grille shutter to the commanded position may also be
based on feedback from a grille shutter position sensor (e.g.,
sensor 118 at FIG. 1). As non-limiting examples, the commanded
position may have been determined based on ECT independent of other
engine operating conditions (e.g., at 308), based on a DFSO event
(e.g., at 310), based on ECT and other engine operating conditions
(e.g., at 312), or based on an estimated oil in fuel dilution level
in addition to ECT and other engine operating conditions (e.g., at
318).
[0081] If the current grille shutter position is a position more
open than the commanded grille shutter position, adjusting the
grille shutter position at 320 may include decreasing the grille
shutter opening by a specified amount (e.g., adjusting the opening
by a specified percentage or degree of inclination). Decreasing the
grille shutter opening may include adjusting the grille shutter
opening from a first open position to a second open position, the
first open position a more open position than the second. As
another example, decreasing the grille shutter opening may include
adjusting the grille shutter opening from an open position to a
closed position. In a still further example, decreasing the grille
shutter opening may include adjusting the grille shutter opening
from a first closed position to a second closed position, the
second closed position more closed than the first. In this way, by
decreasing a grille shutter opening, temperatures within the engine
compartment may increase and promote fuel vaporization, thereby
decreasing fuel in oil dilution.
[0082] As an alternate example, if the current grille shutter
position is a position less open than the commanded grille shutter
position, adjusting the grille shutter position at 320 may include
increasing the grille shutter opening by a specified amount (e.g.,
adjusting the opening by a specified percentage or degree of
inclination). Increasing the grille shutter opening may include
adjusting the grille shutter opening from a first open position to
a second open position, the second open position a more open
position than the second. As another example, increasing the grille
shutter opening may include adjusting the grille shutter opening
from a closed position to an open position. In a still further
example, increasing the grille shutter opening may include
adjusting the grille shutter opening from a first closed position
to a second closed position, the first closed position more closed
than the first. In this way, by adjusting the grille shutters to a
more open position adequate ventilation of the engine during an
acceleration event may be provided.
[0083] In this way, by selectively adjusting a grille shutter
opening responsive to fuel in oil dilution, and adjusting a grille
shutter opening further based on one more of an engine coolant
temperature, charge air cooler temperature, and
acceleration/deceleration, fuel in oil dilution may be addressed
while providing a desired amount of control over engine
temperatures and fuel efficiency.
[0084] In some examples, 320 may also include adjusting one or more
other engine operating conditions to reduce oil dilution. Such
adjustments include but are not limited to advancing a fuel
injection timing, increasing a fuel pressure, and performing a
split fuel injection under various conditions. In this way, engine
operating parameters may be adjusted based on the oil dilution
amount to reduce oil dilution and improve emissions. Routine 300
then terminates.
[0085] As discussed herein, oil may be diluted with fuel during
engine operation. For example, oil dilution with fuel may increase
when engine operating temperatures are below an evaporative
threshold. Oil dilution may be monitored based on an ambient
temperature, an engine block temperature, an engine coolant
temperature, an engine speed, an engine load, a fuel injection
pressure, a fuel injection timing, an engine operation time, a
commanded air-to-fuel ratio, and an engine air-to-fuel ratio as
described with respect to FIG. 4, and based on the oil dilution
amount, engine operating parameters such as fuel injection timing
may be adjusted to reduce oil dilution. During some conditions, oil
dilution may be further monitored based on measurements from an
intake air oxygen sensor (e.g., IAO2 sensor 88 at FIG. 1) of PCV
gases via a PCV fuel compensation strategy, as further elaborated
with respect to FIG. 5. In one example, the PCV fuel compensation
strategy includes estimating a hydrocarbon content of the intake
air, and may be selectively performed when both of EGR and fuel
vapor purge are not operating. The adjustment of grille shutters
based on oil dilution will be further elaborated with respect to
FIGS. 4-6.
[0086] Turning now to FIG. 4, it shows an example routine 400 which
depicts a method for estimating an oil dilution amount. In one
example routine 400 is executed as part of a routine for adjusting
engine operating conditions including a grille shutter opening
based on the estimated oil dilution amount (e.g., at 314 in routine
300). The oil dilution amount is estimated based on one or each of
two methods, namely an oil dilution model and/or a PCV fuel
compensation strategy, the particular method used determined based
on engine operating conditions. In the depicted example, the PCV
fuel compensation strategy is used to estimate the oil dilution
amount when push-side PCV flow is present and both of EGR and fuel
vapor purge are disabled, while the oil dilution model may
otherwise be used to estimate the oil dilution amount. As a
specific example, if EGR and fuel vapor purge are disabled but
push-side PCV is not present (e.g., if boost conditions are not
present, thereby disallowing push-side PCV flow), an oil dilution
model is used to estimate the oil dilution amount. In an alternate
example, the estimated oil dilution amount may be based on the oil
dilution model during all conditions, and the estimate may be
further based on PCV fuel compensation strategy when push-side PCV
flow is present and both of EGR and FVP are disabled. In alternate
examples where EGR system 18 further includes a DPOV sensor, oil
dilution may be estimated based on a PCV fuel compensation strategy
when the push-side PCV flow is present, EGR is enabled, and FVP is
disabled.
[0087] In the depicted example, the engine system of the vehicle
executing routine 400 includes each of a PCV system, an EGR system,
and an FVP system (e.g., motor vehicle 102 at FIG. 1). However, in
alternate examples, routine 400 may be executed by a vehicle with a
PCV system but without EGR or FVP, in which case a PCV compensation
strategy may be used to estimate an oil dilution level when
push-side PCV flow is present.
[0088] Adjusting engine operating conditions in response to the
estimated oil dilution amount may include further closing the
grille shutters under certain conditions. For example, in response
to the estimated oil dilution amount being greater than a threshold
level, a grille shutter position may be adjusted to a position that
is more closed than the current grille shutter position. In this
way, engine temperatures may be increased to vaporize more fuel in
the oil, thereby reducing the dilution of oil. In response to the
estimated oil dilution amount being less than the threshold amount,
oil in fuel dilution level may not be used to adjust the grille
shutter position.
[0089] At 410, routine 400 may include estimating and/or measuring
one or more engine operating conditions. Engine operating
conditions may include an ambient temperature, an engine
temperature, an engine speed, an engine load, an injection
pressure, an injection timing, a duration of engine operation, an
engine air-to-fuel ratio, etc. Upon determining the engine
operating conditions, the routine may proceed to 412.
[0090] At 412, an estimated rate of deposit of fuel into oil is
estimated based on injection pressure, injection spray angle, start
of injection (SOI), and inducted air charge temperature. At 414, if
engine temperatures are above a lower threshold temperature, an
estimated rate of vaporization may be determined based on an
assumption of the fuel species that accumulate in the oil and the
vapor pressures of these species. Assuming the fuel species that
accumulate in the oil may include assuming a class of hydrocarbons
present in the fuel provided to the direct injector. In one
example, the lower threshold temperature may be a fuel vaporization
temperature determined based on properties of the fuel and oil in
the engine system.
[0091] At 420, the routine may include determining an oil dilution
model based on the engine operating conditions. In one example, the
oil dilution model may be based on a difference between a commanded
air-to-fuel ratio and an engine air-to-fuel ratio as determined
from an exhaust sensor. The commanded air-to-fuel ratio may be
determined based on an amount of fuel injection determined by the
engine controller to maintain the exhaust gas products at
stoichiometric conditions. The engine air-to-fuel ratio may be
determined based on a reading from the exhaust UEGO sensor (e.g.,
sensor 64 at FIG. 1).
[0092] For example, during cold start conditions, when it is
determined that the controller is commanding more fuel to maintain
the engine air-to-fuel ratio at stoichiometry, it may be inferred
that the fuel is lost to the oil pan by passing the piston rings.
Accordingly, when the commanded air-to-fuel ratio is richer than
stoichiometry and the exhaust sensor based engine air-to-fuel ratio
is at stoichiometry, an oil dilution amount may be increased. The
amount of increase may be based on the integrated difference
between the commanded air-to-fuel ratio and the engine air-to-fuel
ratio as determined via the exhaust oxygen sensor. Likewise, when
the controller is commanding less fuel to maintain the engine
air-to-fuel ratio at stoichiometry, it may be inferred that excess
fuel (to maintain stoichiometric engine air-to-fuel ratio) may come
from the PCV system. Accordingly, the oil dilution amount may be
decreased. The amount of decrease may be based on the integrated
difference between the commanded air-to-fuel ratio and the engine
air-to-fuel ratio.
[0093] In another example, the oil dilution model may be based on a
duration of engine operation and a fuel injection timing. For
example, during engine operation in a warm state (e.g. engine
temperature may be at or greater than a threshold temperature,
catalyst may be at or greater than a catalyst light-off
temperature, etc.), the controller may determine if late fuel
injection was carried out at one or more cylinders since engine
start. As such, late fuel injections may be performed during a cold
start condition to improve particulate emissions. In other words,
the start of fuel injection timing during cold start operations may
be retarded from start of fuel injection timings when engine is not
operating in cold start conditions. However, late fuel injection
may increase dilution of oil in the crankcase. Therefore, if late
fuel injection was performed since engine start, the controller may
determine if a duration of engine operation in the warm state is
greater than a threshold duration. The threshold duration may be
based on an amount of fuel that was injected late since engine
stop. For example, it may take a duration of time with engine
operating in warm conditions after cold-start to combust the excess
fuel in the PCV system (excess fuel in the PCV system may be due to
late fuel injection timings utilized during the cold start to
reduce particulate matter and particle number emissions).
Therefore, if the duration of engine operation in the warm state is
greater than the threshold duration, excess fuel in the PCV system
may be combusted. Consequently, the oil dilution amount may be
reduced. However, if it is determined that the duration of engine
operation is not greater than the threshold duration, excess fuel
in the PCV system may not be combusted. As a result, oil dilution
amount may not be decreased.
[0094] As such, an amount by which the oil dilution amount may be
increased or decreased when engine is not operating in cold start
conditions may be based on a duration of engine operation in the
warm state, and an amount of fuel injected with late fuel
injection. For example, the amount of increase of oil dilution
amount may increase as the duration of engine operation in the warm
state decreases. Further, the amount of increase of oil dilution
amount may increase with an increase in the amount of fuel injected
late. Similarly, the amount of decrease of oil dilution amount may
increase as the duration of engine operation in the warm state
increases, and as the amount of fuel injected late decreases.
[0095] In a still further example, the oil in fuel dilution model
may be based on current vehicle data as well as past data,
including but not limited to engine temperature history and ambient
temperature history. In further examples, including the above
example, the oil in fuel dilution model may estimate a dilution
level based on past dilution level estimates in addition to an
estimated rate of deposit of fuel into oil and an estimated rate of
vaporization of fuel from oil. Specifically, a difference in an
estimated rate of deposit and an estimated rate of vaporization of
fuel from oil may be determined, and this rate may be applied to a
previous estimate for oil in fuel dilution (e.g., via an integral)
to determine a current oil in fuel dilution estimate.
[0096] Continuing at 430, a decision is made based on whether the
EGR and fuel vapor purge systems in the vehicle are enabled or
disabled. In one example, EGR may be enabled based on engine
speed-load conditions where EGR benefits can be achieved. For
example, EGR may be enabled when engine speed is above a threshold
speed (e.g., above an idle speed) and when engine load is above a
threshold load (e.g., above a minimum load). The controller may
determine EGR is enabled if an EGR valve is open and EGR is flowing
through an EGR passage (e.g., EGR valve 49 and EGR passage 51 shown
in FIG. 1). In the presence of recirculated exhaust gas, a
controller may not be able to distinguish the effect on EGR
hydrocarbons on the oxygen sensor relative to those of PCV
hydrocarbons. Therefore estimating a fuel in oil dilution level
while EGR is enabled may degrade the accuracy of such estimates. As
used herein, the EGR refers to a low pressure EGR recirculated from
an exhaust manifold, downstream of a turbine, to an intake
manifold, upstream of a compressor.
[0097] In one example, a fuel vapor canister (such as fuel vapor
canister 104 shown in FIG. 1) may be purged when a canister load is
higher than a threshold, the engine is running, and a purge valve
is open. As such, if purge air is received in the intake aircharge,
purge hydrocarbons (HCs) may be ingested along with exhaust
residuals in the EGR. In the presence of purge air, a controller
may not be able to distinguish the effect on purge hydrocarbons on
the oxygen sensor relative to those of PCV hydrocarbons. Therefore
estimating a fuel in oil dilution level while purge is enabled may
degrade the accuracy of such estimates.
[0098] Thus, if one of EGR and purge are enabled at 430, the method
continues on to 434 to estimate the oil dilution amount via the oil
dilution model introduced above. In an alternate embodiment, the
method may close the purge valve and the EGR valve to permit the
use of the PCV fuel compensation strategy for estimating an oil
dilution amount. In other words, the PCV fuel compensation strategy
is only performed to estimate an oil dilution amount if there is no
other reductant contribution from EGR or purge air in the intake
passage. If both EGR and purge are disabled, routine 400 instead
proceeds to 432 to estimate an oil dilution amount via the PCV fuel
compensation strategy.
[0099] In an alternate example, oil dilution estimates may be made
only via the PCV fuel compensation strategy, and thus only based on
intake oxygen sensor measurements. In such an example, the grille
shutters may not be adjusted based on an oil dilution amount if
conditions do not allow for the execution of the PCV fuel
compensation strategy. Thus, a method for adjusting a grille
shutter opening responsive to fuel in oil dilution (e.g., routine
300 at FIG. 3) may be performed when push-side PCV flow is active,
and not performed when push-side PCV flow is inactive. Further, as
described herein, the adjusting may not be performed when one of an
EGR valve and an FVP valve are open. Put another way, the adjusting
may not be performed when one of an EGR system and an FVP system
are enabled, but may be performed when both systems are
disabled.
[0100] Continuing at 432, a PCV fuel compensation strategy may be
used to estimate a fuel in oil dilution amount based on one or more
of a PCV flow rate, various engine temperature, and an inferred
hydrocarbon content of intake gas, the inferred hydrocarbon content
based on intake oxygen sensor measurements (e.g., IAO2 sensor 88 at
FIG. 1). An example PCV fuel compensation strategy is shown by
routine 500 at FIG. 5, and is described in further detail
therein.
[0101] Alternatively, at 434, an oil dilution amount may be
estimated based on the oil dilution model. For example, the oil
dilution model may be applied to an oil quality monitor to obtain
an estimated oil dilution amount.
[0102] In one example, when it is determined that the controller is
commanding more fuel to obtain a stoichiometric engine air-to-fuel
ratio, the oil quality monitor maintaining a current oil dilution
amount may be adjusted by incrementing the oil dilution amount. The
amount of increase may be based on the difference between the
commanded air-to-fuel ratio and the engine air-to-fuel ratio. As
the difference between the commanded air-to-fuel ratio and the
engine air-to-fuel ratio increases, the amount of increase of oil
dilution amount may increase.
[0103] In another example, when it is determined that the
controller is commanding less fuel to maintain the engine
air-to-fuel ratio at stoichiometry, the oil quality monitor
maintaining a current oil dilution amount may be adjusted by
decreasing the oil dilution amount.
[0104] In still another example, when the commanded air-to-fuel
ratio and the engine air-to-fuel ratio are at stoichiometry, it may
be inferred that there is no fuel in the oil. That is, oil dilution
may be zero.
[0105] In yet another example, during a vehicle cold start, a cold
start oil dilution quality score may be generated based on the
modeled oil dilution. Subsequently, a rolling average of a cold
start oil dilution quality score may be determined, and an
estimated oil dilution amount may be obtained based on the rolling
average.
[0106] Upon estimating the oil dilution amount, the routine may
proceed to 440. At 440, the estimated amount is applied to memory
for use as an oil dilution amount in other routines. For instance
the estimated amount may be used in routine 300 (at FIG. 3) to
determine whether the oil dilution amount is above or below a
threshold amount. The estimated amount may also be applied as a
value in one or more oil dilution models, for instance it may be
provided as an input for an oil minder or for oil quality monitor
logic. Routine 400 then returns to a higher-order routine, or
terminates.
[0107] FIG. 5 depicts a PCV fuel compensation strategy as detailed
by routine 500. In the depicted embodiment, PCV fuel compensation
strategy includes determining a hydrocarbon content of the intake
air based on an intake air oxygen sensor (e.g. IAO2 sensor 88 at
FIG. 1) and converting the HC content estimate to an estimated oil
dilution amount, and is executed as part of routine 400 (at 440)
for estimating an oil dilution amount.
[0108] Routine 500 begins at 502 where it is determined whether
both of an EGR system and a fuel vapor purge system are enabled. As
mentioned above, the PCV fuel compensation strategy is only used
for estimating an oil dilution amount if there is no other
reductant contribution from EGR or purge air in the intake passage.
In this way, the presence of any hydrocarbons as inferred via a
measurement from the IAO2 sensor may be assumed to be from the
crankcase via the PCV system, and not from exhaust gas or from fuel
tank vapors. In this way, an oil dilution amount may be more
accurately estimated via the IAO2 sensor. If one or more of the EGR
system and fuel vapor purge system are enabled, routine 500
proceeds to 508 where oil dilution is not estimated via the PCV
fuel compensation strategy but instead estimated via the oil
dilution model discussed with reference to FIG. 4. After 508,
routine 500 returns to 440 at FIG. 4.
[0109] At 504, it is determined whether PCV blow-by gases are
flowing through the push-side conduit (e.g., conduit 74 at FIG. 1)
into the intake air passage (e.g., intake passage 12 at FIG. 1) via
push-side port 101. Determining whether push-side PCV gas flow is
present may include determining the state of a PCV valve (e.g., PCV
valve 78 at FIG. 1) which admits air into the intake passage. For
example, it may be determined that push-side flow is present if the
PCV valve is closed (thereby preventing pull-side flow) and that
push-side flow is not present if the PCV valve is open (i.e.,
pull-side PCV flow is present rather than push-side PCV flow). In
another example, an engine controller may determine that push-side
PCV gas flow is present by determining that boosted conditions are
present (e.g., if pressure sensor 86 indicates an intake manifold
pressure greater than barometric pressure), and may determine that
push-side PCV gas flow is not present if boosted conditions are not
present. If push-side PCV flow is present, routine 500 proceeds
directly to 512 to determine a hydrocarbon content of intake air
based on IAO2 measurements. If the PCV gases are not flowing
through the push-side flow conduit and into the intake air passage,
routine 500 proceeds to 506 to attempt to activate PCV push-side
flow.
[0110] The controller determines at 506 whether engine conditions
allow for the enabling the measurement of PCV gases via the IAO2
sensor. Estimating the oil dilution amount via the PCV fuel
compensation strategy requires push-side flow of the PCV system in
order to measure the hydrocarbon content of gases in the crankcase.
As such the engine must be boosted to provide these gases. As one
example, PCV push-side flow may only be present during boosted
conditions (e.g., wherein intake air is being boosted by the
turbocharger). In this example, if intake air is not being boosted
by the turbocharger and conditions do not allow for boosting to
begin, PCV push-side flow conditions are not met. In this case,
routine 500 proceeds to 508 where oil dilution is not estimated via
the PCV fuel compensation strategy but instead estimated via the
oil dilution model discussed with reference to FIG. 4. After 508,
routine 500 returns to 440 at FIG. 4. If PCV push-side flow is not
present but conditions allow for boosting to begin, boost is
activated (thereby activating push-side flow) and routine 500
proceeds to 512.
[0111] Continuing at 512, the oxygen content at the intake air
oxygen sensor and is used to determine a hydrocarbon content of the
intake air. As the amount of PCV HCs delivered to the intake
passage (upstream of the compressor) increases, such as when PCV
push-side flow is present during boosted conditions, the
hydrocarbons react with oxygen at the sensing element of the intake
oxygen sensor. The oxygen is consumed and water and carbon dioxide
is released. As a result, the estimated oxygen concentration is
reduced, even though other variables such as intake manifold
pressure may remain constant.
[0112] Furthermore, the effect of PCV push-side flow on intake
oxygen measurements may be learned as a function of boost pressure.
As discussed above, PCV push-side flow may be active (e.g.,
flowing) during all boosted conditions (e.g., wherein intake air is
being boosted by the turbocharger) and may be inactive during
non-boost conditions. During engine operating conditions when EGR
is not enabled (e.g., EGR valve is closed and/or EGR is not
flowing) and fuel vapor purge is not enabled (e.g., fuel canister
purge valve is closed), the PCV impact on the intake oxygen sensor
output may be determined. Specifically, during these conditions,
intake oxygen may be measured by the intake oxygen sensor while the
engine is not boosted. Then, the controller may turn on boost and
again measure the intake oxygen at the intake oxygen sensor. A
change in intake oxygen between the non-boosted and boosted
conditions may then represent the contribution of PCV flow to the
decrease in intake oxygen from a reference point (e.g., zero
point). This decrease in intake in oxygen may be attributed to an
increase in hydrocarbon content from the PCV gases.
[0113] At 514, the HC measurement made at 512 is used to estimate
an oil dilution amount. In one example, an expected hydrocarbon
content may be determined by relating one or more of a crankcase
temperature, crankcase pressure, fuel injection rate, fuel
injection mass, the chemical properties of the fuel (e.g., how the
specific hydrocarbon content of the fuel may affect the oxygen
sensor), and blow-by rate to an expected hydrocarbon content, or
vaporized fuel concentration, within the crankcase. The controller
may compare the estimated hydrocarbon content from 512 to this
expected hydrocarbon content, and determine an oil dilution amount
based on the difference. In one example, the model for determining
the oil dilution amount may assume that the difference between the
estimated hydrocarbon content from 512 and the expected hydrocarbon
content is diluted into the oil. At 516 this estimated oil dilution
amount is applied to memory for use in other algorithms, for
example by routine 400. Routine 500 then terminates.
[0114] FIG. 6 provides an example routine 600 for adjusting a
commanded grille shutter position based on engine coolant
temperature and an oil dilution amount. Routine 600 may be executed
as part of a method which adjusts a front-end engine airflow based
on engine coolant temperature, and responsive to an oil dilution
amount greater than a threshold temperature, selectively adjusts
the engine front-end airflow based on each of engine coolant
temperature and the oil dilution amount. In such an example,
adjusting the engine front-end airflow may includes one of
increasing or decreasing the engine front-end airflow, and
adjusting an engine front-end airflow adjusting device (e.g.,
adjustable grille shutters) from a first position to a second
position.
[0115] As a specific example, increasing the airflow may include
adjusting an engine front-end airflow adjusting device (e.g., an
adjustable grille shutter) from a fully closed position to a fully
open position, and decreasing the airflow may include adjusting the
engine front-end airflow adjusting device from a fully open
position to a fully closed position. However, as an alternate
example, increasing the engine front-end airflow may include
adjusting the engine front-end airflow adjusting device from a
first mid-point position to a second mid-point position, the second
mid-point position more open than the first, while decreasing the
engine front-end airflow may include adjusting the engine front-end
airflow adjusting device from a first mid-point position to a
second mid-point position, the second mid-point position less open
than the first.
[0116] Selectively adjusting the front-end engine airflow may
include, if engine oil dilution is above the threshold amount but
engine coolant temperature is greater than an upper threshold
temperature, adjusting based on engine coolant temperature and not
on the oil dilution amount. Selectively adjusting the front-end
engine airflow may further include, if engine oil dilution is above
the threshold amount but engine coolant temperature is less than a
lower threshold temperature, adjusting based on engine coolant
temperature and not the engine oil dilution amount. In this way,
engine front-end airflow may be adjusted to control engine
temperatures, and further flexibility may be used to address oil
fuel in oil dilution.
[0117] In one example, routine 600 is executed as part of routine
300 at 318. Within the context of routine 300, a commanded position
has already been determined at 312 and routine 600 is executed to
further adjust the commanded position based on whether the oil
dilution amount estimated at 314 is above or below the threshold
level. Some of the steps of routine 300 have been incorporated into
FIG. 6 for emphasis of the depicted method.
[0118] Routine 600 begins at 602 where it is determined whether ECT
is great than an upper threshold temperature. If ECT is greater
than the upper threshold temperature, routine 600 proceeds to 604
where the commanded position is not adjusted based on oil dilution,
and thus the engine front-end airflow is only adjusted based on
engine temperature. If ECT is less than the upper threshold
temperature, routine 600 instead proceeds to 606.
[0119] At 606 it is determined whether ECT is less than a lower
threshold temperature. If ECT is less than the lower threshold
temperature, routine 600 proceeds to 608 where the commanded
position is not adjusted based on oil dilution, and thus the engine
front-end airflow is only adjusted based on engine temperature. If
ECT is greater than the lower threshold temperature, routine 600
instead proceeds to 610.
[0120] At 610 it is determined whether the oil dilution amount is
greater than the threshold amount. As one example, during
conditions wherein push-side PCV flow is present, the oil dilution
amount may be determined via intake oxygen sensor measurements, for
instance via routine 500 as described with reference to FIG. 5. If
the oil dilution amount is greater than the threshold amount,
routine 600 proceeds to 612. At 612, the commanded position is
further adjusted based on the oil dilution amount. In this way,
responsive to oil dilution greater than a threshold amount, engine
front-end airflow may be adjusted based on each of engine coolant
temperature and oil dilution amount. After 612, routine 600 returns
to routine 300, or in alternate examples, terminates.
[0121] In one example, adjusting the engine front-end airflow based
on each of the coolant temperature and the oil dilution amount
includes decreasing the engine front-end airflow in response to the
coolant temperature at or below an upper threshold temperature and
the oil dilution above the upper threshold amount, and increasing
the engine front-end airflow in response to the coolant temperature
above the upper threshold temperature and the oil dilution above
the upper threshold amount.
[0122] Continuing at 610, if the engine oil dilution amount is
below the threshold amount, the commanded position is not adjusted
based on oil dilution at 614. In this way, the engine front-end
airflow may be adjusted based on engine coolant temperature. After
614, routine 600 returns to routine 300, or in alternate examples,
terminates.
[0123] FIG. 7 provides an example routine 700 for adjusting a
commanded grille shutter position based on an oil dilution amount.
Routine 700 includes, during a first condition, adjusting a
commanded grille shutter position based on an estimated oil
dilution, and during a second condition, selectively increasing
durations of future commanded positions. Further, if the oil
dilution amount does not fall below a threshold amount after a
specified duration, the grille shutters are adjusted to be fully
closed until the oil dilution amount is below the threshold amount.
The first condition may include when the commanded position is less
open than a specified upper threshold opening, while the second
condition may include when the commanded position is at least as
open as the upper threshold opening. Selectively increasing the
durations of future commanded positions may include increasing
durations of future commanded positions only when they are below a
lower threshold opening. In one example, the upper threshold
opening may be specified as 100% open (fully open), and the lower
threshold opening may be specified as 0% open (fully closed).
[0124] In this way, if engine cooling is currently desired, fuel in
oil dilution may be addressed at a later event when grille shutter
closure is already desired. Note that the commanded position may
based on ECT and acceleration/deceleration in addition to various
engine operating conditions, and executing routine 700 may further
adjust the commanded position based on an oil dilution amount. In
one example, routine 700 may be executed as part of a method for
adjusting a grille shutter opening based on an estimated oil
dilution amount. Specifically, routine 700 may be executed as part
of routine 300 at 318, the commanded position having been
determined at 312. Routine 300 may then utilize the adjusted
commanded position to adjust the grille shutter position at 320, or
alternatively increase the duration of future commanded positions
less than a threshold opening.
[0125] Routine 700 begins at 702 where a commanded position and an
estimated oil dilution amount are received. In the depicted
embodiment, receiving an estimated oil dilution amount includes
receiving a desired grille shutter position associated with the
estimated oil dilution amount. At 704, it is determined whether the
commanded position is at least as open as the upper threshold
opening described above. It will be understood that the upper
threshold opening may be any value within the range of the grille
shutters. The threshold level may be determined based on various
engine conditions, including but not limited to engine coolant
temperature, engine oil temperature, and ambient air temperature.
As one example, the threshold level may be 90% open and commanded
positions more open than the threshold level indicate a need for
engine cooling via grille shutter air flow. If the commanded
position is equal to or more closed than the threshold opening,
routine proceeds to 706. If the commanded position is more open
than the threshold opening, routine 700 proceeds to 708. In this
way, fuel in oil dilution may be addressed when a commanded
position is already a closed position based on other engine
conditions, and addressing fuel in oil dilution may be delayed if
the commanded position is an open position (e.g., for controlling
engine temperatures).
[0126] At 706 the commanded position is adjusted based on an oil
dilution amount. Adjusting the commanded position based on an oil
dilution amount may include adjusting the commanded position based
on a desired grille shutter opening associated with the estimated
oil dilution amount. The desired grille shutter opening associated
with the estimated oil dilution amount may decrease (i.e., be more
closed) as the dilution amount increases. In one example, the
commanded position may be adjusted from a closed position to a more
closed position, the adjusted commanded position more open than the
desired grille shutter opening based on the dilution amount. In an
alternate example, the commanded position may be adjusted from an
open position to an open position less open than the unadjusted
commanded position. In this example, the adjusted commanded
position is more open than the desired grille shutter opening based
on the dilution amount. In a further example, the commanded
position may have already been fully closed, and the commanded
position is not adjusted. After 706, routine 700 proceeds to
709.
[0127] In other examples, adjusting the commanded position at 706
may include adjusting the duration of the commanded position. For
example, if the commanded grille shutter position was fully closed
based on vehicle acceleration and the position was commanded to be
maintained until the end of the acceleration event, the engine
controller may increase the duration so that the grille shutters
are maintained at the fully closed position after the acceleration
event has ended, thereby improving fuel vaporization in the
crankcase.
[0128] Alternatively, at 708, the commanded position is not
adjusted. Instead a command is executed to selectively increase the
duration of future commanded positions. Specifically, if a future
commanded position is more closed than a lower opening threshold,
the controller may increase the duration for which this commanded
position is held. As discussed above, the lower opening threshold
may be 0%, or may be any closed position greater than 0%. In some
examples, the duration of a specified number of future commanded
positions more closed than the lower opening threshold may be
increased. In other examples, all future commanded positions more
closed than the lower opening threshold may be increased until the
oil dilution amount is below the threshold amount. In some
embodiments, if the lower threshold opening is greater than 0%, the
future commanded positions may be adjusted to be more closed based
on the oil dilution amount.
[0129] At 709 the routine waits for a specified duration for the
intended effects of adjusting a grille shutter closing to be
realized. As a non-limiting example, the specified duration may be
determined based on a rate of engine coolant temperature rise, a
rate of oil temperature rise, vehicle driving conditions, and
vehicle speed. At 710, the oil dilution amount is estimated again
to determine whether increased durations of closed grille shutter
positions has reduced the oil dilution. If the oil dilution remains
above the threshold after the specified waiting duration, the
grille shutters may be fully closed at 714 until the oil dilution
amount has fallen below the threshold amount. Alternatively, if the
grille shutter position was already fully closed, the grille
shutters may be maintained at fully closed until the oil dilution
amount has fallen below the threshold amount.
[0130] After the estimated oil dilution amount has fallen below the
threshold amount, routine 700 may terminate, or may return to a
routine for adjusting a grille shutter position such as routine 300
at FIG. 3. In this way, the grille shutters may be maintained as
fully closed until an estimated oil dilution amount falls below a
threshold amount, and in response to the estimated dilution amount
falling below the threshold amount, the grille shutter position may
be adjusted based at least on engine coolant temperature.
[0131] FIG. 8 shows examples of adjusting grille shutters based on
ECT, oil dilution level, and additional engine operating
conditions. The sequence of FIG. 8 may be provided by the system of
FIGS. 1-2 according to the method of FIG. 3. Specifically, graph
800 shows changes in grille shutter percentage opening at plot 810,
changes in engine coolant temperature at plot 820, changes in pedal
position at plot 830, and changes in the estimated oil dilution
amount at plot 840. A lower threshold temperature T1 and an upper
threshold temperature T2 are associated with ECT, and when ECT is
greater than temperature T1 and less than temperature T2, ECT is
referred to as being within the threshold temperature range. The
pedal position (PP) may be one of the additional engine operating
conditions that grille shutter position is based on when ECT is
within the threshold temperature range. In the depicted example, a
PP below threshold position PP1 correlates to vehicle deceleration,
a PP above threshold position PP2 corresponds to vehicle
acceleration, and any PP between the threshold positions
corresponds to positions which maintains vehicle speed. In
alternate embodiments, additional or alternative engine operating
conditions, such as CAC efficiency, may be used to determine grille
shutter position. Vertical markers t1-t5 represent times of
interest during the operating sequence.
[0132] Prior to time t1, the ECT is greater than the lower
threshold temperature T1, and less than the upper threshold
temperature T2. The pedal position is greater than PP2, indicating
acceleration. The grille shutter percentage opening is 0% such that
the grille shutters are fully closed responsive to the engine
coolant temperature being within the threshold temperature range
and the detected vehicle acceleration, thereby blocking engine
front-end airflow and improving vehicle aerodynamics. Other engine
operating conditions which are not depicted, such as charge air
cooler temperature, may also influence the current grille shutter
opening. While oil dilution is depicted as below the threshold
amount, the grille shutter opening may be adjusted to or maintained
at a closed position responsive to acceleration regardless of the
state of oil dilution. By blocking engine front-end airflow,
temperatures within the engine compartment may increase.
[0133] At time t1, ECT increases above the threshold temperature
T1. In response, grille shutter positions are determined based on
ECT alone and not determined based on pedal position (i.e.,
acceleration/deceleration), oil dilution level, or any additional
engine operating condition. Put another way, the engine front-end
airflow may be increased in response to ECT greater than an upper
threshold temperature regardless of the status of other operating
conditions such as pedal position and oil dilution. Specifically,
the airflow may be increased in response to a high ECT when pedal
position indicates either of deceleration and acceleration, and
when oil dilution is either above or below the threshold dilution
amount. The percentage opening of the grille shutters increases as
ECT increases after time t1, eventually reaching 100% open (e.g.,
the maximal percentage opening). In this way, engine front-end
airflow is increased in response to engine coolant temperature
greater than an upper threshold and vehicle acceleration.
[0134] At time t2, when the ECT decreases below the upper threshold
temperature T2 and remains above the lower threshold temperature
T1, the controller may recalibrate the grille shutter position
based on engine coolant temperature in addition to vehicle
acceleration/deceleration. In the depicted example, the grille
shutter position is immediately recalibrated. However in other
examples the grille shutter position may be gradually adjusted from
a first position to the recalibrated position. Soon after time t2,
pedal position drops below PP1, indicating deceleration. Oil
dilution is below the threshold amount. Accordingly, responsive to
deceleration and engine coolant temperature above the lower
threshold temperature, engine airflow is increased by adjusting the
grille shutters from a first midpoint position to a second midpoint
position, the second midpoint position more open than the first. In
this way, engine temperatures may be reduced in anticipation of a
future vehicle acceleration.
[0135] At time t3, the estimated oil dilution amount rises above
threshold amount 842. Additionally, pedal position indicates
deceleration and ECT is within the threshold temperature range.
Responsive to these conditions, the engine front-end airflow is
decreased by reducing the grille shutter opening percentage. In the
depicted example, the grille shutter position is adjusted from a
first mid-point position to a second mid-point position, the second
mid-point position more closed than the first. The airflow is
further decreased as the oil dilution amount increases.
Additionally, the second mid-point position is a closed position.
In other examples, the grille shutter position may be adjusted to
the fully closed position responsive to ECT within the threshold
temperature range, detected deceleration, and an oil dilution
amount above a threshold amount.
[0136] At time t4, the estimated oil dilution falls below the
threshold amount. ECT is within the threshold temperature range,
and PP is below PP1, indicating deceleration. In response to the
ECT being below the upper threshold temperature, deceleration, and
oil dilution amount being above the threshold amount, the grille
shutter position is adjusted to a more open position to increase
airflow. Further, as PP begins decreasing, the grille shutter
position becomes more open. The grille shutter position is
maintained at the more open position while pedal position continues
to indicate deceleration.
[0137] At time t5, ECT falls below the lower threshold temperature
T1. Pedal position still indicated deceleration and oil dilution is
below the threshold amount. In response to ECT below the threshold
temperature, the engine front-end airflow is reduced by adjusting
the grille shutter opening to a more closed position. Specifically,
the grille shutter is adjusted to the fully closed position. The
engine front-end airflow may be reduced in response to ECT less
than a lower threshold temperature regardless of the status of
other operating conditions such as pedal position and oil dilution.
Specifically, the airflow may be reduced in response to a low ECT
when pedal position indicates either of deceleration and
acceleration, and when oil dilution is either above or below the
threshold dilution amount. In this way, engine coolant temperature
may be maintained within a specified temperature range, and when
this condition is satisfied, airflow may be controlled based on
engine operating conditions such as acceleration/deceleration and
oil dilution.
[0138] In this way, vehicle grille shutters may be adjusted based
on ECT in order to provide cooling airflow to the engine. When ECT
is below a threshold, the controller may adjust the grille shutters
based on ECT and additional engine operating conditions.
Furthermore, when an oil dilution amount is above a threshold, the
grille shutters may be further adjusted based on the oil dilution
amount. However, when ECT is above the threshold, the controller
may adjust the grille shutters based on ECT only.
[0139] Thus a method is provided for an engine front-end airflow
adjusting device, comprising adjusting the engine front-end airflow
based on each of vehicle acceleration/deceleration and engine
temperature, and in response to an oil dilution amount above an
upper threshold, adjusting the engine front-end airflow based on
each of vehicle acceleration/deceleration, engine temperature, and
the oil dilution amount. As described above, the adjusting the
airflow adjusting device based on each of vehicle
acceleration/deceleration and engine temperature according to the
provided method includes decreasing the engine front-end airflow in
response to vehicle acceleration and coolant temperature below an
upper threshold temperature, increasing the engine front-end
airflow in response to vehicle acceleration and coolant temperature
above an upper threshold temperature, increasing the engine
front-end airflow in response to vehicle deceleration and coolant
temperature above a lower threshold temperature, and decreasing the
engine front-end airflow in response to vehicle deceleration and
coolant temperature below a lower threshold temperature.
[0140] Further, adjusting the engine front-end airflow based on
each of acceleration/deceleration, engine temperature, and the oil
dilution includes: increasing the engine front-end airflow in
response to vehicle acceleration, coolant temperature above an
upper threshold temperature, and oil dilution above a threshold
amount; increasing the engine front-end airflow in response to
vehicle deceleration, coolant temperature above an upper threshold
temperature, and oil dilution above a threshold amount; decreasing
the engine front-end airflow in response to vehicle acceleration,
coolant temperature below an upper threshold temperature, and oil
dilution above a threshold amount; decreasing the engine front-end
airflow in response to vehicle acceleration, coolant temperature
above a lower threshold temperature, and oil dilution above a
threshold amount; decreasing the engine front-end airflow in
response to vehicle acceleration, coolant temperature below a lower
threshold temperature, and oil dilution above a threshold amount;
decreasing the engine front-end airflow in response to vehicle
deceleration, coolant temperature below an upper threshold
temperature, and oil dilution above a threshold amount; decreasing
the engine front-end airflow in response to vehicle deceleration,
coolant temperature above a lower threshold temperature, and oil
dilution above a threshold amount; and decreasing the engine
front-end airflow in response to vehicle deceleration, coolant
temperature below a lower threshold temperature, and oil dilution
above a threshold amount.
[0141] As a result, a technical effect of the invention is achieved
by adjusting the grille shutters based on oil dilution amount,
thereby providing a desired level of heating to the engine and
increasing fuel vaporization in the crankcase when oil dilution is
detected. Further, another technical effect of the invention is
achieved by adjusting the grille shutters based on oil dilution
amount in addition to other engine operating conditions such as
acceleration/deceleration. As a result, engine performance and fuel
economy may be improved while additionally addressing fuel in oil
dilution.
[0142] Note that the example control and estimation routines
included herein can be used with various engine and/or vehicle
system configurations. The control methods and routines disclosed
herein may be stored as executable instructions in non-transitory
memory and may be carried out by the control system including the
controller in combination with the various sensors, actuators, and
other engine hardware. The specific routines described herein may
represent one or more of any number of processing strategies such
as event-driven, interrupt-driven, multi-tasking, multi-threading,
and the like. As such, various actions, operations, and/or
functions illustrated may be performed in the sequence illustrated,
in parallel, or in some cases omitted. Likewise, the order of
processing is not necessarily required to achieve the features and
advantages of the example embodiments described herein, but is
provided for ease of illustration and description. One or more of
the illustrated actions, operations and/or functions may be
repeatedly performed depending on the particular strategy being
used. Further, the described actions, operations and/or functions
may graphically represent code to be programmed into non-transitory
memory of the computer readable storage medium in the engine
control system, where the described actions are carried out by
executing the instructions in a system including the various engine
hardware components in combination with the electronic
controller.
[0143] It will be appreciated that the configurations and routines
disclosed herein are exemplary in nature, and that these specific
embodiments are not to be considered in a limiting sense, because
numerous variations are possible. For example, the above technology
can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine
types. The subject matter of the present disclosure includes all
novel and non-obvious combinations and sub-combinations of the
various systems and configurations, and other features, functions,
and/or properties disclosed herein.
[0144] The following claims particularly point out certain
combinations and sub-combinations regarded as novel and
non-obvious. These claims may refer to "an" element or "a first"
element or the equivalent thereof. Such claims should be understood
to include incorporation of one or more such elements, neither
requiring nor excluding two or more such elements. Other
combinations and sub-combinations of the disclosed features,
functions, elements, and/or properties may be claimed through
amendment of the present claims or through presentation of new
claims in this or a related application. Such claims, whether
broader, narrower, equal, or different in scope to the original
claims, also are regarded as included within the subject matter of
the present disclosure.
* * * * *